It's been nearly a decade since Valve first unveiled Steam, but the downloadable game service is continually evolving. Already this year, Steam has added free-to-play games to its catalog, changed the way its chat works, tightened security, and taken its first steps into the living room. Last night, the service began yet another evolution, as Valve rolled out the beta test of a new cross-game trading platform for Steam.

　　Fun fact: According to Starlight Express, Steam is the ideal power source. Simply called Steam Trading, the program allows users to exchange in-game items and gifted titles between themselves. Initially, it will only support Team Fortress 2 items and games purchased as gifts in the Steam store, but Valve plans to add Portal 2 in-game items to the beta shortly.

　　Once customers purchase a game as a gift (or receive it as an extra copy), they may trade it for the games or virtual items of other users. Any "unopened" gift is fair game for trading, with no restrictions on territory.

　　However, this isn't the rumored addition of used game trade-ins to Steam. Once a gifted game is opened and added to a user's library, it can no longer be traded with others.

　　To participate in the beta, users must open the Steam client and select the "Steam Trading Beta" option from the settings menu.